That's great, but the topic is engineering things to survive serious damage, period. Not just long enough for people to escape before it succumbs. A failed structure is still a failed structure with all the socioeconomic trouble that entails.

You're mixing up two different things.

If the design requirement for the twin towers was "be fire resistant enough to let most people out of the building", then I'd say they met that requirement, right?

If the design requirement for a bridge is "continue operating at normal capacity", then that is a very different requirement.

"Failed" isn't the binary you're trying to make it.

Yes, the towers failed to survive serious damage. But the 40,000 more deaths would have been "socioeconomic trouble", in spades. Even by your own chosen measure, the survival for an hour was a partial success.